Apparatus for corrugating relatively thin deformable sheet material for use as the primary surface plates of fixed type heat exchangers or recuperators for gas turbines or the like is known in the art. In one technique, as disclosed in U.S. Pat. No. 3,892,119, by Kenneth J. Miller et al., issued July 1, 1975, the corrugating apparatus receives substantially flat and relatively thin deformable sheet material which is then shaped into a relatively narrowly grooved corrugated configuration having a determined number of fins per inch, the cnfiguration being serpentine. The apparatus is such that the corrugations in the sheet material are formed individually in a sequential manner to minimize any stretching or tearing of the material.
More particularly, the flattened material is transported to a fin shaping station which has a plurality of forming blades on either side of the material. These blades are actuated or moved sequentially into contact with the flattened sheet material to form one fin of the corrugated sheet. After forming this one fin, the blades are moved away from the sheet and the latter indexed or moved one fin position so that the blades again can be actuated to contact the sheet and form another fin.
For example, with such prior corrugation apparatus, a first lower blade is raised into contact with one side of the flattened sheet material and then a second upper blade on the other side of the material is lowered into a groove of a previously formed fin to act as a clamp for the forming of the next fin. These two blades are on opposite sides of one wall of the previously formed fin. Next, a third upper blade is lowered into contact with the flattened material to fold such material around the first blade and thereby form a wall of the fin being formed. Finally a fourth lower blade is raised to fold the material around the third blade, and thereby form another wall of the fin being formed.
As is known, it is desirable to obtain as high a fin density as possible. With more fins per inch, there will be a greater surface area per unit volume, resulting in greater heat transfer because of the increased surface area. The above-described aparatus is capable of producing about 40 fins per inch, which is a significant improvement over other known apparatus which can form the sheet material into corrugations providing only about 25 fins per inch.